1. Field of the Invention
The present invention relates to a road lane recognizing apparatus for recognizing a lane defined by white lines appearing in a road surface image represented by an actual image signal obtained through a picturing means such as a picture and camera or the like mounted on a vehicle for picturing a road surface before the vehicle.
2. Description of the Related Background Art
A steering control system is disclosed in, for example, JP-A-5-334595 which system enables a motor vehicle to automatically cruise while its steering is controlled on the basis of an image signal obtained by a television camera mounted on the front part of the vehicle. In such steering control system, an image of a road surface in front of the vehicle is usually obtained by the television camera, white lines being detected from the obtained image by a lane recognizing apparatus. The current vehicle-self position is detected by a vehicle-self position detecting means such as a device using the GPS (Global Positioning System) or the like. A steering amount of the steering is calculated on the basis of the current vehicle-self position on the lane defined by the white lines, and a steering actuator is driven in accordance with the calculated steering amount.
In the steering control system, the steering is controlled depending on the road surface image obtained by the television camera, as mentioned above. When, therefore, the television camera is incorrectly mounted on the vehicle or, otherwise, there is an inclination (roll) in the vehicle, such a problem should occur that the road surface image is inclined and the white line position, that is, a road lane cannot be accurately recognized because of the inclination of the road surface image. Consequently, there is uncertainty in positional relation of the recognized position and attitude of the vehicle relative to the lane and, therefore, a steering control amount cannot be accurately calculated and it is difficult to control the vehicle cruising, as desired.